Republic of the Philippines
Department of Education
Region V - Bicol
LEARNING ACTIVITY SHEET
Science 10 Quarter 4 Week 6
Name:
_________________________________
Grade & Section: _________________________________
I.
Score: ______________
Date: ______________
Introductory Concept
The chemical reactions we have described are only a tiny sampling of the infinite number of
chemical reactions possible. How do chemists cope with this overwhelming diversity? How do they predict
which compounds will react with one another and what products will be formed? The key to success is to
find useful ways to categorize reactions. Familiarity with a few basic types of reactions will help you to
predict the products that form when certain kinds of compounds or elements come in contact.
Even though chemical compounds are broken up and new compounds are formed during a
chemical reaction, atoms in the reactants do not disappear, nor do new atoms appear to form the products.
In chemical reactions, atoms are never created or destroyed. The same atoms that were present in the
reactants are present in the products—they are merely reorganized into different arrangements. In a
complete chemical equation, the two sides of the equation must be present on the reactant and the product
sides of the equation.
II.
Learning Skills from the MELCs
Apply the principles of conservation of mass to chemical reactions. (S10MT-IVe-g-23)
Objectives:
1. Classify chemical reactions according to their types, based on how atoms are grouped or regrouped.
2. Apply the concept of Law of Conservation of Mass in balancing chemical equations.
III.
Activity
Activity 1
A. Read the guide card below about the classifications of chemical reactions.
GUIDE CARD
COMBINATION (Synthesis) REACTION: A reaction when 2 or more reactants combine to form a single product. The general formula for
this reaction is :
A+B →
AB
DECOMPOSITION REACTION: In this reaction, a single reactant breaks down into simpler ones. (2 or more products). This is the
reverse of combination reaction. The general formula for this reaction is: AB → A + B
SINGLE DISPLACEMENT (Replacement) REACTION: This is when one element replaces another element from a compound. The more
active element takes the place of the less active element in a compound. The general formula for this reaction is: A + BC → AC + B
DOUBLE DISPLACEMENT REACTION (Metathesis): This is when the positive ions (cations) and negative ions (anions) of different
compounds switch places, forming two entirely different compounds. The general formula for this reaction is: AB + CD → AD + CB
COMBUSTION (Burning) REACTION: This is when oxygen combines with a hydrocarbon (compound containing hydrogen and carbon)
to form a water and carbon dioxide. Example of which is the burning of butane gas C4 H 10 + O2 → CO2 + H2O
ACID-BASE REACTION: This is a speacial kind of double displacement reaction that takes place when an acid and base react with each
other. The H+ of the acid reacts with the OH- of the base forming water. The other product is salt. Example of which is:
HCI + NaOH
→ NaCI + H2O
B. Study the given pictures below. Based from the guide card you’ve read, identify what type of chemical
reaction is depicted in each item.
1.
2.
3.
4.
C. Given the chemical equation, identify the types of chemical reaction.
Reaction
1
2
3
4
5
6
7
Chemical Equation
Fe + 𝐶𝑢𝑆𝑂4 →𝐹𝑒𝑆𝑂4 + Cu
Mg + 𝑂2 → MgO
𝐻2 𝑂2 →
𝐻2 𝑂 + 𝑂2
𝑀𝑛𝑂2
→ 𝑁𝑎𝐶2 𝐻3 𝑂2 + 𝐶𝑂2 +
𝐻2 𝑂
𝐶𝑢𝑆𝑂4 + NaOH
→
𝐶𝑢(𝑂𝐻)2 + 𝑁𝑎2 𝑆𝑂4
𝐶𝐻4 +𝑂2 → 𝐶𝑂2 + 2𝐻2 𝑂
𝐻2 𝑆𝑂4 + 𝑁𝑎𝑂𝐻 →
𝑁𝑎2𝑆𝑂4 + 𝐻2 𝑂
𝐻𝐶2 𝐻3 𝑂3 + 𝑁𝑎𝐻𝐶𝑂3
Types of Chemical Reaction
5.
6.
7.
8.
9.
10
11.
Activity 2. Balancing Chemical Equation
Direction: Study the two methods used in balancing chemical equations.
Inspection Method
1. The unbalanced chemical equation
Al + 𝑶𝟐 → 𝑨𝒍𝟐 𝑶𝟑
The unbalanced chemical equation is given to you.
Aluminum reacts with oxygen to produce aluminum oxide. Rewrite
the equation as shown above
2. Make a list
First, identify the elements on the reactant side (left side) and the elements of
the compound are on the product side (right side)
-make a list of all of the elements on each side under the equation for both the
reactants and products as shown on the left side.
-under the reactant’s side, list Al and O
-under the product’s side, list Al and O
Al + 𝑶𝟐 → 𝑨𝒍𝟐 𝑶𝟑
Al:
O:
Al:
O:
3. Identifying the atoms/subscript in each element
Al + 𝑶𝟐 → 𝑨𝒍𝟐 𝑶𝟑
Al:
O:
1
2
Al:
O:
2
3
Put the number of atoms that are in each of the elements.
-on the reactants side, next to Al, put 1
-next to O, put 2
-apply these same rules to each element on the product side.
4. Multiplying the Number of Atoms
Al + 𝑶𝟐 → 𝑨𝒍𝟐 𝑶𝟑
Al:
O:
1x2=2
2x3=6
Al:
O:
2
3x2=6
Notice how the number of atoms next to each element is different from the number of
atoms next to that same element on the product side. In order to balance the chemical
equation, you need to make sure the number of atoms of each element on the reactant
side is equal to the number of atoms of each element on the product side. In order to
make both sides equal, you will need to multiply the number of atoms in each element until
both sides are equal. As shown on the left side, the multiplication of atoms on the reactant
side will affect both elements on the product side.
5. Placing Coefficients in Fronts of Molecules
2 Al +3 𝑶𝟐 → 2𝑨𝒍𝟐 𝑶𝟑
Al:
O:
1x2=2
2x3=6
Al:
O:
2
3x2=6
After you have multiplied the number of atoms of each element until both sides
are equal, you will put the number, the coefficient, of how much you multiplied
the element by and place in front of that element or compound in the equation
as shown in the left side of the box.
On the product side, although both elements did not get multiplied, still place the
number that was multiplied as the coefficient in front of compound.
Inspection Method
6. Check equation
2 Al +3 𝑶𝟐 → 2𝑨𝒍𝟐 𝑶𝟑
Al: 1x2=2
O: 2x3=6
Al:
2
O: 3x2=6
2 Al +3 𝑶𝟐 → 2𝑨𝒍𝟐 𝑶𝟑
Al: 1x2=2
O: 2x3=6
Al:
O:
2x2= 4
3x2=6
After you have placed the coefficients in front of the molecules,
make the list of elements again and check to see if multiplying the
coefficient with the subscript will give you atoms equal on both the
reactants and products sides.
If they are not equal, rework your multiplication.
Apply the Law of Conservation of Mass to get the same number of
atoms of every element on each side of the equation.
7. Balanced chemical equation
4 Al +3 𝑶𝟐 → 2𝑨𝒍𝟐 𝑶𝟑
Al:
O:
1x4=4
2x3=6
Al:
O:
2x2= 4
3x2=6
After you have reworked your multiplication, make the list of
elements again to check to make sure the equation is balanced. If
both sides are equal, you have now balanced the chemical equation
Balance the following chemical equations by using the inspection method, making sure to apply the
principle of the Law of Conservation of Mass.
1. 𝑃4 + 𝑂2 → 𝑃2 𝑂5
IV.
2. Si𝐶𝑙4 + 𝐻2 O → Si𝑂𝟐 + HCl
Analysis
Activity 1
1. How will you identify the types of reaction?
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Activity 2
1. Which method would you prefer, inspection method or algebraic method? Why?
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2. What are the two reasons for balancing chemical equations?
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3. Why is balancing equation important?
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V.
Abstraction
Types of chemical reactions include combination, decomposition, single displacement,
double displacement, acid-base and combustion reactions.
Law of Conservation of Mass states that mass is conserved in a chemical reaction. The
total mass of the reactants is equal to the total mass of the products. No new atoms are created
or destroyed, there was only grouping or regrouping (rearrangement) of atoms.
For a chemical equation to conform to the Law of Conservation of Mass, it has to be
balanced. Chemical equations are balanced by placing the appropriate coefficients before the
symbols or formulas of reactants and products. Certain steps are observed in balancing reactions.
VI.
Application
1. Cite situations where combination, decomposition, single displacement and double
displacement is involved. Give 1 example for each type of reactions.
2. Study the pictures below that illustrate the Law of Conservation of Mass. Answer the questions
below.
a. How many H2 will you use?
b. How many set/s of O2 will you use?